The present inventors found before that Streptomyces sp. KC-7367 (FERM BP-1277) separated from a soil in Maniwa-gun, Okayama, Japan produces a product showing high antifunal activity, further isolated two antifungal products, KA-7367A and KA-7367B from the liquid culture medium, and identified and proposed them (refer to Japanese Laid-open Patent Application No. 6248/89, European Patent Laid-open Specification No. 282,001).
Said antifungal products KA-7367A and KA-7367B are represented by the following formula. ##STR2##
Though the antifungal products KA-7367A and KA-73676B themselves show quite excellent antifungal activity, the present inventors have eagerly made studies to synthesize stable derivatives having by far better antifungal activity, and consequently found that 2-imino derivatives formed by converting a carbonyl group in the 2-position of KA-7367A into an imino exhibit quite high antifungal activity and excellent stability and are useful as antifungal agents; as a result, they have completed this invention.